Experts have advised the Government to lift a controversial blanket ban on homosexual men giving blood, amid fears of blood shortages as younger donors fail to come forward.

But despite a clear recommendation to lift the ban more than a month ago, ministers are dragging their feet – and experts on the advisory committee on the safety of blood, tissues and organs (Sabto) say they have been warned not to talk about the "politically sensitive" situation.

Figures released for Britain's first National Blood Week, ahead of World Blood Donor day on Tuesday, are expected to show that the pool of donors is at risk of depleting. At present there are 1.7 million people on the UK donor list and the NHS will be pushing for more people to sign up.

A panel of medical experts recommended last month that the ban should be relaxed so that gay men who have not had sex within a 12-month period can donate blood. But ministers have so far declined to endorse the experts' decision.

The new recommendation brings the UK in line with many other countries that already permit homosexuals to make blood donations. Health safety experts advised that the ban on men who have had sex with men was no longer medically justified to protect the blood pool from HIV.

One source on Sabto, who had to remain anonymous as the board was "told to keep quiet until ministers had looked at the recommendations", said its decision to relax the rules came thanks to medical advances. Another expert adviser said: "A lot of things have changed and the technology to monitor blood is now automated and much safer, so the likelihood of HIV getting through is highly unlikely."

For bone marrow transplantation, where the same risks apply, the law on gay and bisexual men has already been relaxed to a case-by-case basis. Sometimes it can take several months for HIV antibodies to show in tests, which is why experts want the extra precaution of a year without sex.

Campaigners say the current guidelines are draconian, unnecessary and breach equality law. However, the Department of Health review of them has been held up as a result of ministerial prevarication.

When initially asked last week, the department insisted it had not yet been given any findings, but later conceded: "The findings of the review will be considered by the relevant health ministers and further information on any resulting changes to current blood donation policies will be made available in due course."

The human rights campaigner Peter Tatchell, who plans to take legal action under equality law if the total ban is not lifted, said: "Blood shortages would be far fewer if more non-risk gay and bisexual men could donate. One year is an improvement on the current lifetime ban but it is still a needlessly long exclusion period. I can only assume the delays are due to serious conflict and disagreement."

Jane Firth, 39, from Staffordshire, was given 18 pints of blood after haemorrhaging during childbirth. "I wouldn't have survived if I hadn't had the blood. My liver and kidneys stopped working. It'd be a good thing if they changed the law. As long as you're fit and healthy, it shouldn't matter if you're gay or straight."